Locating targets in the human body by means of ultrasound techniques is well known. In extracorporeal shockwave lithotripsy or disintegration of a concretion or kidney stone in a kidney, ureter, or bladder by means of shockwaves is known. It is the general procedure to use an articulated arm carrying an ultrasonic transducer that both sends out and receives the ultrasound signal. Devices are connected in the articulated arm to indicate the angles between various arm segments, and the angles thereof relative to a base. Movement of such articulated arms is necessarily restricted, and the arms themselves tend to get in the way. The information obtained by such arms and the ultrasound devices carried thereby is fed through a computer to control the position of the lithotripter so that a shockwave generated thereby is focused on the kidney stone or other bodily concretion. Lithotripters have found use in fragmenting or destroying gallstones, as well as kidney stones. It is also sometimes necessary to locate a tumor in the body, or the location of a broken bone to study how well it is mending.